JPS6225843B2 - - Google Patents

Abstract

PURPOSE:To smoothly return the lubricating oil of an overhead-cam-type internal combustion engine, by utilizing the vacuum pump of a vacuum-type brake booster so that the lubricating oil gathering in the top chamber of a cylinder head is forcedly returned to an oil pan. CONSTITUTION:When a brake pedal 20 is not pressed down, an oil passage 27 extending from an oil drain port 26 in a cylinder head 3 is connected to a vacuum pump 19 through a three-way valve 30 so that lubricating oil gathering in the top chamber of the cylinder head 3 is suched out together with a small amount of blow- by gas through the port 26 and the passage 27 by the vacuum pump 19 and then returned to an oil pan 5 through a drain passage 25. More than a prescribed quantity of the lubricating oil is thus prevented from staying in the top chamber 9. When the brake pedal 20 is pressed down for braking, a switch 33 is closed to shift the three-way valve 30 to apply negative pressure to a brake booster 21 so that prescribed braking action is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an overhead cam type internal combustion engine installed in a vehicle such as an automobile, and is a method for quickly circulating lubricating oil for a valve mechanism in a cylinder head into an oil pan. It is related to the device.

Conventionally, lubricating oil after lubricating the valve mechanism in an overhead cam internal combustion engine has been applied to the cylinder block and cylinder head of the internal combustion engine, as described in, for example, Japanese Utility Model Application Publication No. 51-151840. It is well known that oil is returned to the oil pan in the lower part of the crankcase by gravity from a ventilation hole bored to communicate between the upper chamber of the cylinder head containing the valve mechanism and the crankcase. It is as follows.

However, inside this ventilation hole,
The blow-by gas leaking into the crankcase flows upward toward the upper chamber of the cylinder head, and the lubricating oil flows down against the flow of this blow-by gas, making it difficult for the lubricating oil to flow down from the ventilation hole. As a result, lubricating oil tends to accumulate in the upper chamber of the cylinder head, and especially in high engine load and high rotation ranges, the amount of blow-by gas flowing from the crankcase to the upper chamber of the cylinder head increases. This tendency will increase (almost no lubricating oil will flow and will only accumulate). As a result, more lubricant oil accompanies the blow-by gas extracted from the upper chamber of the cylinder head into the engine's intake system or exhaust system, which increases the amount of harmful components in the engine's exhaust gas and increases the amount of lubricant oil consumed. do.

To prevent this, the cross-sectional area of the ventilation hole can be increased, but drilling a hole with too large a cross-sectional area or a large number of holes will lead to a decrease in the strength of the engine. ,
In order to do this while maintaining the strength of the engine, the engine itself had to be made that much larger, resulting in a larger engine.

According to the present invention, an engine mounted on a vehicle such as an automobile equipped with a vacuum brake booster is attached with a vacuum pump that is a vacuum source for the vacuum brake booster in the vehicle. Considering that the engine is in an idling state when braking is not performed, the lubricating oil accumulated in the cylinder head is forcibly returned to the oil pan using the idling section of the vacuum pump. This solves the above-mentioned problems.

For this reason, the present invention provides an overhead cam type vehicle internal combustion engine in which a valve mechanism is built in the upper chamber of the cylinder head, in which an oil drain port is provided at the bottom of the upper chamber of the cylinder head, and an oil passage from the oil drain port is Connected to a vacuum passage from a vacuum brake booster associated with a brake pedal of a vehicle to an inlet of a vacuum pump driven by the internal combustion engine, and at this connection point, in connection with a braking operation of the vehicle, A switching means is provided for switching the suction port of the vacuum pump to communicate with the vacuum brake booster during braking, and to communicate the suction port of the vacuum pump and the oil passage during non-braking; The discharge port of the vacuum pump is connected to the crankcase or oil pan of the internal combustion engine.

With this configuration, when the vehicle is braking by depressing the brake pedal, the vacuum brake booster is in communication with the vacuum pump inlet, but when the brake pedal is not being pressed and the vehicle is not braking, the oil passage is in vacuum. By communicating with the suction port of the pump, the lubricating oil in the upper chamber of the cylinder head is sucked out by the vacuum pump and then returned to the crankcase or oil pan from the discharge port of the vacuum pump. While the vehicle is not braking,
A vacuum pump can force the oil back into the oil pan.

To explain the drawings of the embodiment below, in the drawings, reference numeral 1 indicates an overhead cam type internal combustion engine having a cylinder block 2, a cylinder head 3, a cylinder head cover 4, and an oil pan 5. and an intake manifold 8 having a carburetor 7 is attached,
Further, in the upper surface chamber 9 of the cylinder head 3, a camshaft 10 and a swing arm 1 for the intake valve and exhaust valve are provided.
A valve mechanism 13 such as 1 and 12 is provided, and its upper chamber 9 communicates with the inside of the crankcase 10 through ventilation holes 14 and 15 formed through the cylinder block 2 and cylinder head 3. The blow-by gas leaking into the crankcase 10 passes through the ventilation holes 14 and 15 and reaches the upper chamber 9, and then flows from the gas-liquid separation chamber 16 provided in the cylinder head cover 4 through the blow-by passage 17 to the air cleaner 6, etc. The fuel is discharged into the intake system of the engine or the exhaust system (not shown) of the engine and is combusted. The lubricating oil in the oil pan 5 is sent to various sliding or rotating parts of the engine by a lubricating oil pump (not shown) driven from the crankshaft 18 of the engine, and then is returned to the oil pan 5. Some of the lubricating oil from the lubricating oil pump is transferred to the valve mechanism 1.
Sent to 3.

19 is linked to the crankshaft 18 of engine 1,
Alternatively, a vacuum pump is directly connected to an alternator (not shown) that is linked to the crankshaft 18, 20 is a brake pedal in the vehicle, 21 is a vacuum brake booster that is linked to the brake pedal 20, and 22 is the brake booster. 21 shows vacuum tanks connected through passages 23, and when the brake pedal 20 is stepped on, the booster of the control booster 21 operates the master cylinder with vacuum pressure, thereby applying the brakes from the master cylinder to each wheel of the vehicle. High pressure hydraulic pressure is sent to the wheel cylinders of the device for braking action.

A discharge port 24 of the vacuum pump 19 is connected to the crankcase 10 or the upper part of the oil pan 5 via a passage 25. On the other hand, the cylinder head 3 is provided with an oil drain port 26 for extracting the lubricating oil in the upper chamber 9, and an oil passage 27 from the port 26 and a vacuum passage to the vacuum brake booster 21 are provided. 28 and the vacuum pump 19
A three-way valve 30, such as an electromagnetic solenoid type, is provided at the point connected to the inlet 29 of 19, but the electromagnetic solenoid 3
1, the oil passage 27 is closed while the vacuum passage 28 is switched to communicate with the vacuum pump 19, and an electric circuit 33 connects the electromagnetic solenoid 31 and battery 32 in the three-way valve 30. A switch 33 is provided therein, which is connected to the brake pedal 20 and turns on when the brake pedal 20 is stepped on. In addition, 3
4 indicates a stop lamp that lights up when the brake pedal 20 is depressed.

In this configuration, when the brake pedal 20 is not depressed, the three-way valve 30 communicates the oil passage 27 from the oil drain port 26 in the cylinder head 3 with the vacuum pump 19, so that the lubricating oil accumulated in the upper surface chamber of the cylinder head 3 is removed. After being sucked out by the vacuum pump 19 through the port 26 and passage 27 along with some blow-by gas, it is returned to the oil pan 5 from the discharge passage 25, and the upper surface chamber 9
The lubricating oil that has accumulated is forcibly returned to the oil pan 5 by the vacuum pump 19, and is prevented from accumulating in the upper chamber 9 beyond a certain level. When braking the vehicle, when the brake pedal 20 is depressed, the switch 33 is turned on and the three-way valve 30 is switched to communicate the vacuum passage 28 to the vacuum brake booster 21 with the vacuum pump 19. At the same time as stopping the suction of lubricating oil from the upper chamber 9 of the cylinder head 3, the brake booster 21 is connected to the vacuum pump 1.
9 acts, and the vehicle is strongly braked by the vacuum pressure.

As described above, according to the present invention, with the configuration described in the claims, lubricating oil in the upper surface chamber of the cylinder head can be supplied using the vacuum pump in the vacuum booster of the vehicle when the vehicle is not braking. Since the oil can be forced to flow back into the oil pan, the following effects can be achieved.

Blow-by gas from the crankcase to the upper chamber of the cylinder head increases in the high load/high rotation range of the internal combustion engine, and even if lubricating oil tends to accumulate in the upper chamber of the cylinder head, the Since the frequency of braking operations on the vehicle is low, it is possible to reliably eliminate lubricating oil from accumulating in the upper chamber of the cylinder head.

As a result, the amount of lubricating oil that disappears with blow-by gas can be reduced, and there is no need to increase the cross-sectional area of the ventilation holes provided in the cylinder head and cylinder block, making the internal combustion engine smaller and lighter. can be achieved.

Since the vacuum pump can be simultaneously lubricated by the lubricating oil that flows back to the oil pan via the vacuum pump when the vehicle is not braking, the labor for lubrication of the vacuum pump can be saved and the structure can be simplified.

[Brief explanation of the drawing]

The drawings are diagrams showing embodiments of the invention. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 2... Cylinder block, 3... Cylinder head, 9... Top chamber, 13... Valve mechanism, 2
0...Brake pedal, 21...Vacuum type brake booster, 19...Vacuum pump, 28...Vacuum passage, 26...
Oil drain port, 27...Oil passage, 30...Three-way valve.

Claims (1)

[Claims] 1 In an overhead cam type vehicle internal combustion engine with a built-in valve mechanism in the upper chamber of the cylinder head,
An oil drain port is provided at the bottom of the upper chamber of the cylinder head, and an oil passage from the oil drain port is connected to a vacuum brake booster associated with the brake pedal of the vehicle to the suction of the vacuum pump driven by the internal combustion engine. In connection with the braking operation of the vehicle, this connection point communicates the inlet of the vacuum pump with the vacuum brake booster when braking, and the vacuum passage when not braking. An internal combustion engine characterized in that a switching means is provided for switching the suction port of the pump and the oil passage to communicate with each other, and a discharge port of the vacuum pump is connected to a crankcase or an oil pan of the internal combustion engine. lubricating oil reflux device.